Defect substructure change in 100-m differentially hardened rails in long-term operation

Gromov, V. Е.; Yuriev, A. A.; Ivanov, Yu. F.; Glezer, A. M.; Konovalov, S. V.; Семин, А. П.; Сундеев, Р.В.

doi:10.1016/j.matlet.2017.07.135

Cited by 11 publications

(3 citation statements)

References 11 publications

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“…Two mechanisms of cementite plate fracture under deformation of pearlite structure steel are mainly discussed in scientific literature [20][21][22][23][24][25][26][27][28]. The first mechanism consists in the cutting of the plates by moving dislocations and carrying out the carbon atoms by them to ferrite to the field of stress dislocations.…”

Section: Resultsmentioning

confidence: 99%

Transformations of fine structure and carbon atoms distribution in 100-m differentially hardened rails under long term operation

Yuriev¹,

combine»²,

Gromov³

et al. 2019

VNMSTU

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Using the methods of transmission electron microscopy, the authors of this paper show that the lamellar perlite grains, ferrite-perlite grains and structurally free ferrite grains constitute the main morphological components of category DT350 differentially hardened rails. The level of mechanical properties and the quality of steel rails comply with the Russian standard GOST R 51685-2013. The authors looked at the evolution of the carbide phase and the redistribution of carbon atoms in the surface layers of differentially hardened rails (the passed tonnage is 691.8 million tons) at the depth reaching 10 mm along the rail head centre line and the rail web. The authors found two complementary mechanisms of carbide phase transformation taking place in the surface layers when the rails are in operation: (1) cutting mechanism of cementite particles with the following departure in the bulk ferrite grains or plates (in the perlite structure); (2) cutting mechanism of cementite particles followed by their dissolution, transfer of carbon atoms onto dislocations (in Cottrell atmospheres and dislocation nuclei), transfer of carbon atoms by dislocations in the bulk ferrite grains (or plates) with the following repeated formation of nanosized cementite particles. The first mechanism stands for changing linear dimensions and morphology of carbide particles. The elemental composition of cementite does not see any significant changes. And the structural changes in the carbide can follow the second mechanism. The main cause of cementite dissolution is related to the energy of carbon atoms localized in dislocation nuclei and subgrains, which is higher compared with the cementite lattice. The binding energy 'carbon atom-dislocation' is 0.6 eV, and in cementite it can sometimes be 0.4 eV. It was found that the carbon atoms that stayed in the cementite lattice are located on the lattice defects, i.e. dislocations, grain and subgrain boundaries.

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Section: Resultsmentioning

confidence: 99%

Transformations of fine structure and carbon atoms distribution in 100-m differentially hardened rails under long term operation

Yuriev¹,

combine»²,

Gromov³

et al. 2019

VNMSTU

Self Cite

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show abstract

“…Two mechanisms of cementite plate fracture under deformation of pearlite structure steel are mainly discussed in scientific literature [16][17][18][19][20][21][22][23][24]. The first mechanism consists in the cutting of the plates by moving dislocations and carrying out the carbon atoms by them to ferrite by dislocation stress field.…”

Section: Resultsmentioning

confidence: 99%

Stages and Fracture Mechanisms of Lamellar Pearlite of 100-m-Long Differentially Hardened Rails Under Long-Term Operation Conditions

Yuriev¹,

Gromov

Grishunin

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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Using the methods of transmission electron microscopy, the carbide phase evolution in surface layers of the differentially quenched rails is studied after the passed tonnage of 691.8 million tons at the depth up to 10 mm along the central axis and fillet of rail head. The action of two mutual supplement mechanisms of steel carbide phase transformation in surface layers at rail operation is established: (1) cutting mechanism of cementite particles with the following departure in the volume of ferrite grains or plates (in pearlite structure); (2) cutting mechanism and following dissolution of cementite particles, transfer of carbon atoms on dislocations (in Cottrell atmospheres and dislocation cores), transfer of carbon atoms by moving dislocations into ferrite grains volume (or plates) with the following repeated formation of nanosized cementite particles. The first mechanism is accompanied by the change in linear sizes and morphology of carbide particles. Cementite element composition change is not essential. Carbide structure change can take place during the second mechanism.

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“…One of the factor for the crack development is the value of residual stresses in rail elements [3,4]. In the areas of the sharp crack edges a concentration of stresses can appear, consequently the crack will be developing in this direction rather quickly.…”

Section: Introductionmentioning

confidence: 99%

Strain Stress Model of the Rail with Crack in its Head and Estimation of its Operational Lifetime

Муравьев

Tapkov

Volkova

et al. 2019

MSF

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The most common reason of the fatigue crack appearance is the presence of stresses in the rail. The process of stress strain state simulation for the R65 rail is presented in the paper. Values of residual stresses were modeled and chosen to be maximum allowed by GOST (State Standard): -77 MPa in the rail head, -125 MPa in the web and 106 MPa in rail foot. These stresses match the value-77 MPa measured by the acoustoelastic method from the center of the rolling surface of the rail. The influence of the crack at the highest level of the stress strain state was studied in cases of the maximum train load and its absence. According to results of modeling, stresses in the sharp edge of the crack can exceed the lowest acceptable by GOST (State Standard) value of the yield strength by more than 5 times in case of the presence of the train load. In case of the absence of the train load, the crack does not have a significant influence on the stress strain state. The modelling process was also used to study the influence of the installation temperature difference on the operational lifetime of the rail. The paper presents the description of the influence between the installation temperature difference and the crack initiation. According to modeling results and the rail defect catalogue, rails with the lowest acceptable mechanical characteristics are prohibited to be used after 300∙109 kg and higher tonnage.

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Defect substructure change in 100-m differentially hardened rails in long-term operation

Cited by 11 publications

References 11 publications

Transformations of fine structure and carbon atoms distribution in 100-m differentially hardened rails under long term operation

Transformations of fine structure and carbon atoms distribution in 100-m differentially hardened rails under long term operation

Stages and Fracture Mechanisms of Lamellar Pearlite of 100-m-Long Differentially Hardened Rails Under Long-Term Operation Conditions

Strain Stress Model of the Rail with Crack in its Head and Estimation of its Operational Lifetime

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